Magnetic storage devices are often included in computer systems to provide high-capacity secondary storage or data archival. Magnetic storage includes magnetic tape systems, hard disk drives, and the like. Magnetic storage generally comprises a recording medium and an access device. The access device includes a head assembly having write elements that generate magnetic fields to encode data onto the recording medium, and read elements that sense magnetic fields of the recoding medium to read data. The head assembly can also include elements for reading servo pattern(s) written to the recording medium during manufacture. The head assembly is aligned with the recording medium by sensing and following the servo pattern(s).
In particular, the head assembly senses the servo pattern(s) to produce a servo signal(s), referred to as a “read-back signal(s).” The read-back signal(s) can be digitized and processed to derive position information for aligning the head assembly to the recording medium. The magneto-resistive element used to sense the servo pattern(s) is sensitive to temperature changes and thermal transients. Such temperature changes can be caused, for example, by a particle on the recording medium, which impacts the head and causes a heating/cooling cycle. Such temperature/thermal effects can add a large baseline disturbance to the servo pattern read-back signal(s) (e.g., large amplitude, low frequency noise components).